NAME

SYNOPSIS

ARGUMENTS

Tcl_Interp *interp (in) Refers to the interpreter the
embedded configuration
information is registered for.
Must not be NULL.
const char *pkgName (in) Contains the name of the
package registering the
embedded configuration as ASCII
string. This means that this
information is in UTF-8 too.
Must not be NULL.
const Tcl_Config *configuration (in) Refers to an array of
Tcl_Config entries containing
the information embedded in the
binary library. Must not be
NULL. The end of the array is
signaled by either a key
identical to NULL, or a key
referring to the empty string.
const char *valEncoding (in) Contains the name of the
encoding used to store the
configuration values as ASCII
string. This means that this
information is in UTF-8 too.
Must not be NULL.
______________________________________________________________________________

DESCRIPTION

The function described here has its base in TIP 59 and provides
extensions with support for the embedding of configuration information
into their binary library and the generation of a Tcl-level interface
for querying this information.
To embed configuration information into their binary library an
extension has to define a non-volatile array of Tcl_Config entries in
one if its source files and then call Tcl_RegisterConfig to register
that information.
Tcl_RegisterConfig takes four arguments; first, a reference to the
interpreter we are registering the information with, second, the name
of the package registering its configuration information, third, a
pointer to an array of structures, and fourth a string declaring the
encoding used by the configuration values.
The string valEncoding contains the name of an encoding known to Tcl.
All these names are use only characters in the ASCII subset of UTF-8
and are thus implicitly in the UTF-8 encoding. It is expected that keys
are legible English text and therefore using the ASCII subset of UTF-8.
In other words, they are expected to be in UTF-8 too. The values
associated with the keys can be any string however. For these the
contents of valEncoding define which encoding was used to represent the
characters of the strings.
Each element of the configuration array refers to two strings
containing the key and the value associated with that key. The end of
the array is signaled by either an empty key or a key identical to
NULL. The function makes no copy of the configuration array. This means
that the caller has to make sure that the memory holding this array is
never released. This is the meaning behind the word non-volatile used
earlier. The easiest way to accomplish this is to define a global
static array of Tcl_Config entries. See the file
"generic/tclPkgConfig.c" in the sources of the Tcl core for an example.
When called Tcl_RegisterConfig will
(1) create a namespace having the provided pkgName, if not yet
existing.
(2) create the command pkgconfig in that namespace and link it to
the provided information so that the keys from configuration and
their associated values can be retrieved through calls to
pkgconfig.
The command pkgconfig will provide two subcommands, list and get:
::pkgName::pkgconfig list
Returns a list containing the names of all defined keys.
::pkgName::pkgconfig get key
Returns the configuration value associated with the
specified key.
TCL_CONFIG
The Tcl_Config structure contains the following fields:
typedef struct Tcl_Config {
const char *key;
const char *value;
} Tcl_Config;